Refactor: tools: Pass node to crm_resource.c:clear_constraints()

If options.host_uname != NULL, then we already got the node in main() or
exited with an error. (Or if we didn't get the node in main() because
scheduler is NULL, then clear_constraints() would segfault.)

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>